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# Data representation

Selecting the type of representation (or graph) depends on the type of data.

- The most common forms of representation for
**categorical**(or categorised)**data**are the bar chart or pie graph. - For
**numerical data**, the number of data values will affect the selection. - The most appropriate form of representation for
**smaller numerical data sets**is likely to be the stacked dot plot or the stem-and-leaf plot. These are adaptable for comparing two data sets. - Histograms are a useful graphical form for
**large numerical data sets**. Box plots, which show a summary of the data in five values, are also useful for large data sets.

Other representations should also be considered. A scatter plot is appropriate for showing an association between two variables measured on the same cases.

## Linking graphs to data types

The type of data collected will influence the possible graphical representations that can be sensibly used.

## Creating pie graphs

Although pie graphs are not explicitly mentioned in the *Australian Curriculum: Mathematics*, they are encountered every day in the media and other subject areas. Hence they are a relevant topic for good teaching.